Printing and display systems that employ a scanned laser beam or beams, to write on a surface are well known. In some systems it is advantageous to use a number of GaAs semiconductor lasers. It is difficult to deliver the power from these lasers in a uniform, close-packed array of beams.
One solution to this problem is to couple the laser power into optical fibers, form a close-packed array with the ends of the fibers and image this array onto the writing surface. This approach was described by Dewey and Crow in the IBM Journal of Research and Development, Vol. 26, No. 2, March 1982. This article describes the use of a parallel array of eight fibers with the end of the fiber array polished flat. A means of coupling the power from an array of GaAs lasers into an array of optical fibers is described by Comerford, U.S. Pat. No. 4,079,404.
In the article by Dewey and Crow (Op. Cit) the writing head comprises the fiber array and a small imaging lens. This head is translated across the surface of a liquid crystal cell by a scanning mechanism and the laser power is coupled to the head through the flexible fiber-optic cable. The head must produce an array of beams on the writing surface that has uniform focus and intensity, and is not distorted. Moreover, the mass of the writing head should be minimized and hence the lens should be small and simple. A simple lens, having one or two elements, has imperfections that make these requirements more difficult to achieve as the number of elements in the fiber array is increased. These imperfections include field-curvature, causing non-uniform focus for a straight parallel array; distortion, and non-uniform collection of light from the fibers.
The patent to Tiefenthal U.S. Pat. No. 3,936,841 describes a photocomposing system in which a fiber-optic face plate is used as a field flattening element. The fibers in the face plate are either parallel, or in an angled arrangement or a combination of both arrangements. No mention or use is made of the refraction of the light beams at the surface of the fibers.
The patent to Kitano et al, U.S. Pat. No. 3,666,347 describes the use of a bundle of optical fibers as a field-flattener for a spherical lens. The ends of all fibers are perpendicular to both the lens and to the flat field.
None of these references teaches or suggests an angled array of optical fibers having the surface polished to a curved shape which delivers an array of beams that are refracted at the surface of the fibers and converge at the entrance pupil of an imaging lens.